Nucleoside diphosphate kinases (NDPKs) are crucial to keep the high triphosphate nucleotide levels in the biological process. The enzymatic mechanism has been extensively described; however, the structural characteristics and kinetic parameters have never been fully determined. In Schistosoma mansoni, NDPK (SmNDPK) is directly involved in the pyrimidine and purine salvage pathways, being essential for nucleotide metabolism. The SmNDPK enzymatic activity is the highest of the known purine metabolisms when compared to the mammalian NDPKs, suggesting the importance of this enzyme in the worm metabolism. Here, we report the recombinant expression of SmNDPK that resulted in 1.7 and 1.9 Å apo-form structure in different space-groups, as well as the 2.1 Å SmNDPK.ADP complex. The binding and kinetic assays reveal the ATP-dependence for enzyme activation. Moreover, in situ hybridization showed that SmNDPK transcripts are found in reproductive organs and in the esophagus gland of adult worms, which can be intrinsically related with the oviposition and digestive processes. These results will help us fully understand the crucial participation of this enzyme in Schistosoma mansoni and its importance for the pathology of the disease.

核苷二磷酸激酶（NDPK）对于在生物过程中保持高三磷酸核苷酸水平至关重要。酶促机理已被广泛描述。但是，尚未完全确定其结构特征和动力学参数。在曼氏血吸虫中， NDPK（Sm NDPK）直接参与嘧啶和嘌呤的挽救途径，这对核苷酸代谢至关重要。所述的Sm相比哺乳动物NDPKs时，提示在蜗杆代谢这种酶的重要性NDPK酶促活性是最高的已知的嘌呤代谢的。在这里，我们报告Sm的重组表达NDPK，导致1.7和在不同的空间基团1.9，脱辅基形式的结构，以及在2.1埃的Sm NDPK.ADP复杂。结合和动力学分析揭示了ATP依赖性的酶激活。此外，原位杂交表明，Sm NDPK转录本存在于成虫的生殖器官和食道腺中，这可能与产卵和消化过程有内在联系。这些结果将帮助我们充分了解这种酶在曼氏血吸虫中的关键参与及其对疾病病理的重要性。